Interfacial tensions between liquid iron and slag were examined for CaO-SiO2 binary and CaO-SiO2-Al2O3 ternary slag systems. The influences of FeO, MgO, B2O3, TiO2, BaO and ZrO2 in slag on the interfacial tension were also investigated by varying these oxides from 1-30wt% in the CaO-SiO 2 binary or CaO-SiO2Al2O3 ternary slag systems. The interfacial tensions were determined by the sessile drop technique under argon atmosphere at 1 853 K. An X-Ray radiographic technique was employed to image the profile of molten iron drop in a slag bath and the interfacial tensions between slag and iron were obtained from the drop shape analysis. In examining the effect of slag composition on the interfacial tension, the oxygen in liquid iron and its impact on the interfacial tension was taken into consideration. The interfacial tension was found slightly increased with increasing CaO/SiO2 ratio in CaO-SiO2 slag, and with increasing MgO content in the slag. A decrease of interfacial tension was found with increasing FeO in slag. Only minor changes in the interfacial tension were observed with varying the slag composition in the CaO-SiO2-Al 2O3 ternary slag system and the influences of B 2O3, TiO2, BaO, and ZrO2 in slag on the interfacial tension were found insignificant.
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